Noiseless elevator safety stop



2 Shoots-Sheet l I E=, f Tb March 8, 1927.

W. F. MCMAHON NOISELESS ELEVATOR SAFE-TY STO? Filed Dec 9. 1924 ar h 8 w. F. McMAHoN NOISELESS ELEVATOR SAFETY STOP Filed Dec. 9. 1924 2 Shouts-Shut 2 Patented Mar. 8, 1927.

httfi WILLIAM FREDERCK MoMAI-ION, OF RVERSDE, GALIFORNI..

NOISELESS ELEVATOE SAFETY STO?.

Application filed December 9, 1924.

This invention relates to new and useful improvements in elevator or inclined conveyor safety stop mechanism as applied to bucket elevators. While the invention is shown applied to bucket elevators it may obviously be manufactured for any kind of an elevator or inclined conveyor and used to equally good advantage.

rlhis invention includes several important objects among' which may be noted firstcThat of mechanism; which makes accidental reversal, or running down of a bucket eleva.- tor under load impossible when the electric current to the operating mechanism is shut oni. Second: 1t will increase the eiiciency of a bucket elevator or inclined conveyor by preventing the loaded conveyor to reverse itself or carry the load back into the pit or boot. Third: rlhe entire mechanism is noiseless.

lilith these and other objects in view the invention resides and consists in the construction and novel combination and arrangement of parts hereinafter more fully described and illustrated in the accompanying drawings, and pointed out in the claim hereto appended, it being understood that various changes in the form, proportion, size and minor details of construction within the scope of the claim may be resorted to without departure from the spirit or sacrificing any of the advantages of the invention.

Similar characters of reference denote like or corresponding parts throughout the several figures of the accompanying drawing forming a part of this specification and upon which Figure 1, is a longitudinal side view of a bucket elevator. Figure 2, is an end view of a bucket elevator sho-wing the operating mechanism. Figure 3, is a view of the noiseless elevator safety stop on a larger scale showing the construction of same. Figure el, is a wiring diagram showing the method of connecting the solenoid with the motor circuit.

Referring in detail to the characters of reference marked upon the drawings.

1 represents buckets, that contain material, and are lifted by means of chain 2 and head sprocket 3, the head sprockets 3 are keyed to shaft 4: which is rotated by spur gear 5 through means of a pinion gear 6 on countershaft 7 and motor 9.

As this bucket elevator and operating mechanism is of standard construction and Serial No. 754,744.

is well known I shall therefore describe only the parts pertaining to my improvement as all other descriptions would be superfluous.

As before stated, this noiseless elevator safety stop is shown agplied to bucket elevators. These so called bucket elevators are adapted to convey various kinds of materials in buckets mounted at intervals on one or two strands of chain. They are operated at suicient speed to discharge their load over the head sprocket by centrifugal force. rfhe head sprocket which operates the strands of chain, is driven by an electric motor.

YIn

oase of accident or a. sudden shutting off of the electric current the loaded elevator will reverse itself and carry its load back into the pit or boot` 8, this is not only annoying and expensive 4but often dangerous. To pre vent this reversal action taking place l have provided a silent ratchet wheel mechanism, the ratchet in this case being keyed to the head sprocket operating mechanism and the pawl is mounted on a structure adjacent to the elevator and is operated by a spring to throw it in engagement with the teeth in the ratchet wheel when the electric current to the motor is shut off, thus preventing the elevator ruiming back, and a solenoid, that is -magnetized by the electric current to the motor, to hold the said pawl out of engagement with the teeth in the ratchet wheel when the elevator is lifting the load.

The ratchet wheel 10 which is keyed on the countershaft 7 is a solid cylindrical disc having angular teeth, several in number on its outer edge, and is prevented from running back by pawl 11 which is a metal bar having on one end portion an angular tooth formation of the same shape as the angular teeth on the ratchet wheel and it fulcruins on a pin 12 which is supported by two solid pillow blocks 13 located on each side of the pawl 11. T he other end portion of the pawl 11 is an outward disposed lug having a hole in its end to take the bolt 14 that attaches the link bar l5 to saine. I have provided this link bar 15, which is a rectangular shaped bar having a bolt hole on each end, to take care of the slight misalignment due to lever motion when the solenoid plunger 16 moves in its constrained longitudinal motion, the solenoid 17 which is of standard construction and the principle of which is well known, when magnetized, pulls the pawl 11 out of engagement with the teeth in the ratchet wheel 10v The helical extension spring lSserves to pull the pawl l1 into engagement with the teeth of the ratchet wheel thus preventing the ratchet wheel running down when the solenoid 17 is demagnetized. l have provided a hole in the linlr end portion oi' the pawl ll to take one end of the spring and the other end portion of the spring will be fastened to approved construction to a structural member 20 adjacent to the elevator.

The solenoid 17 is magnetized by the same circuit a-b .that supply current from the main held lines ato the motor. I have provided a standard electric controller 19 the principle of which is well known, to start or shut off the current to the motor.

Having now particularly described and ascertained the nature oi this invention and in what manner the same is to be performed, I declare that what l claim and desire to secure by Letters Patent is.

In an elevating mechanism, a driven element, an electric motor including a drive shaft, positively acting power transmitting mechanism between said shaft and the driven element whereby the latter is driven from the motor, a ratchet wheel keyed to the motor shaft between the motor and said power transmitting mechanism, a pawl co-V operating with the ratchet wheel, a solenoid in circuit with the motor, a core for said solenoid connected with the pawl whereby the latter is held out of engagement with the ratchet while the motor is operating, and means moving the pawl into engagement with the ratchet upon the power to the motor being shut oil and the solenoid being de* energized, whereby the elevating mechanism is positively held against backwardl movement.

WILLAM FREDERICK MGMAHON. 

